1. Field of the Invention
The present invention relates to surface treatment processes for copper articles and, particularly, to a surface treatment process for a metal article made of copper or an alloy thereof.
2. Description of Related Art
Metal articles made of beryllium-copper alloy, with a high-quality mechanical performance and a high conductivity, have tremendous applications in many industries.
During manufacture of the articles, some impurities or contaminants, e.g., oils or metal oxides, can be easily introduced onto surfaces of the articles, which may deteriorate the decorative appearance and/or the performance of the articles. Thus, the beryllium-copper alloy articles usually require a surface cleaning process for removing, e.g., the oil contaminants and/or metal oxide impurities.
The oil contaminants can be removed in a degreasing process, which is carried out in an alkaline cleaning agent, for example, sodium hydroxide or sodium carbonate. The metal oxide impurities can be removed in an acid cleaning process, which is carried out in an acid solution, such as nitric acid and/or sulfuric acid.
However, the surfaces of the articles can be prone to oxidation while being exposed to air, which may, for example, result in the formation of yellow stains on the surfaces.
Therefore, a surface treatment process for a metal article is desired in order to overcome the above-described shortcomings.